If a highly experienced airline captain decided to continue on three, that's okay with me, having read some of the more rational posts on the R&N thread.
WIth a whole series of diversion fields across the USA, the decision was made with a lot of options and could be charged at any time in the first few hours of flight, whilst overflying the continental USA and Canada.
What would be interesting would be to understand why the Atlantic crossing was made at FL290 - was this an ATC imposition? Its not entirely clear to me, from what I've read, whether 290 was an operational limit due to 3 engined flight.
If it was due only to ATC, why wasn't the service a little more flexible for a flight on 3?